We wouldn't call it a sin. After all, in this day and age it's hard to completely avoid worldly music. A lot of music is fairly neutral from a spiritual perspective. Some music is dangerous, however. We certainly need to be careful and prayerful about what kind of music we listen to on a regular basis. A lot of music, though not evil in and of itself, can lead a person down a pathway that takes him away from God. In other words, the music itself may not be sinful but may influence a person toward sin.